.header-container{
    display: flex;
    justify-content: space-between;
}

.header-container .inp{
 flex: 1;
 height: 40px;
 line-height: 40px;
 box-sizing: border-box;
 padding: 0 12px;
 border-radius: 6px;
 margin-right: 12px;
 border: 1px solid #ccc;
}
.header-container .btn{
    height: 40px;
    padding: 0 24px;
}